FORTEZA-50 is a volumetric bi-static microwave sensor that generates an invisible detection zone between a transmitter and receiver. When an intruder crosses the detection zone, an alarm is generated. FORTEZA-50 provides perimeter security of any object that needs protection against unauthorized intrusion from outside (industrial plants, airports, power stations, private houses, etc.) Operation on 24,15 GHz allows to: - use the sensor in many countries all over the world without getting approval for frequency use; - minimize the influence of different types of interference; - provide narrow detection zone and make it possible to use the sensors on different sites. Configuration of sensors using special software (under Windows) via USB allows to set the optimal operation mode, also remotely from the guard room via RS-485 interface. 4 frequency letters eliminate the influence of adjacent sensors. Like this it is possible to put several sensors near each other.